I had a dinner when I was about 5wks, my friend assumed we'd all share a bottle of wine, as we would normally do! I had to key my BIL in and I'd switch glasses across the table with him. So they'd fill my glass, I'd pretend to sip, then when BIL had almost finished his glass we'd swap.

No one noticed!

Taking drinks you are offered, then leaving them, ditching them somewhere or palming them off to DH I reckon is the best option! No lies to complicate things!